This invention relates to speed sensing differential axle assemblies. More particularly, the invention relates to placement of sensing devices within an axle system, particularly with respect to the differential case thereof.
There are numerous prior art axle assemblies which provide speed sensing mechanisms within differential axle housings. Most involve a placement at the ring gear flange of the differential assembly, or are directly affixed to a trunnion extending from and typically integral with the ring gear flange. There are many drawbacks to the placement of a pickup element in either of the latter positions. One major drawback is the heat generated by the toothed element rotating in the circulating oil within the carrier housing.
An additional drawback relates to the use of pressed rings containing teeth for registration with the pickup element, thus requiring additional parts, extra tooling and machining, potential seating problems for the extra parts, and increased runout which causes transducer sensing problems. Finally, where such speed sensing systems are placed on the ring gear differential flanges, the tolerances can be affected by bending distortions of the ring gear under various dynamic loading conditions, as will be appreciated by those skilled in the art.